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<p>Aluminum-based sacrificial anodes are extensively utilized in marine cathodic protection systems due to their low density, favorable electrochemical activity, and high current efficiency. This study investigates the influence of silicon addition and T6 heat treatment on the microstructure, hardness, and sacrificial anode performance of Al–6.5Mg–xSi alloys containing 1.5, 3, and 6&#xa0;wt% Si. Microstructural analysis confirmed an <i>α</i>-Al matrix with Mg<sub>2</sub>Si as the predominant secondary phase, while increasing Si content transformed the Mg<sub>2</sub>Si morphology from coarse flake-like structures to a refined Chinese-script eutectic network. T6 treatment promoted partial dissolution and redistribution of Mg<sub>2</sub>Si phases, resulting in precipitation strengthening and enhanced hardness in the higher-Si alloys. Electrochemical polarization studies revealed that T6 treatment shifted the corrosion potential (Ecorr) toward more negative values, indicating enhanced anodic activation; however, the simultaneous increase in corrosion current density (Icorr) indicated increased self-corrosion activity. Among the investigated compositions, the as-cast Al–6.5Mg–6Si alloy exhibited the best sacrificial anode performance, achieving an anode capacity of approximately 2781&#xa0;Ah/kg with uniform dissolution behavior. In contrast, T6 treatment increased anodic consumption and reduced current efficiency in the high-Si alloy. Post-corrosion SEM analysis further confirmed that the refined Chinese-script Mg<sub>2</sub>Si morphology promoted relatively homogeneous dissolution, whereas the heat-treated alloys exhibited increased electrochemical heterogeneity. The results demonstrate that silicon addition strongly influences anodic performance, while T6 heat treatment primarily improves mechanical properties rather than sacrificial anode efficiency.</p>

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Influence of Silicon Content and T6 Heat Treatment on Microstructure and Sacrificial Anode Performance of Al–6.5Mg Alloys

  • 期刊论文

  • 发表日期：

    2026年7月27日

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  • Tushal K. Kyada,
  • Sonam M. Patel,
  • Indravadan B. Dave

摘要

Aluminum-based sacrificial anodes are extensively utilized in marine cathodic protection systems due to their low density, favorable electrochemical activity, and high current efficiency. This study investigates the influence of silicon addition and T6 heat treatment on the microstructure, hardness, and sacrificial anode performance of Al–6.5Mg–xSi alloys containing 1.5, 3, and 6 wt% Si. Microstructural analysis confirmed an α-Al matrix with Mg2Si as the predominant secondary phase, while increasing Si content transformed the Mg2Si morphology from coarse flake-like structures to a refined Chinese-script eutectic network. T6 treatment promoted partial dissolution and redistribution of Mg2Si phases, resulting in precipitation strengthening and enhanced hardness in the higher-Si alloys. Electrochemical polarization studies revealed that T6 treatment shifted the corrosion potential (Ecorr) toward more negative values, indicating enhanced anodic activation; however, the simultaneous increase in corrosion current density (Icorr) indicated increased self-corrosion activity. Among the investigated compositions, the as-cast Al–6.5Mg–6Si alloy exhibited the best sacrificial anode performance, achieving an anode capacity of approximately 2781 Ah/kg with uniform dissolution behavior. In contrast, T6 treatment increased anodic consumption and reduced current efficiency in the high-Si alloy. Post-corrosion SEM analysis further confirmed that the refined Chinese-script Mg2Si morphology promoted relatively homogeneous dissolution, whereas the heat-treated alloys exhibited increased electrochemical heterogeneity. The results demonstrate that silicon addition strongly influences anodic performance, while T6 heat treatment primarily improves mechanical properties rather than sacrificial anode efficiency.